CLINICAL FEATURES Medical Assignment Help

Hypothyroidism may produce many symptoms. The classical picture of the slow, dry-haired, thick-skinned, deep-voiced patient with weight gain, cold intolerance, bradycardia and constipation makes the diagnosis easy; the term ‘myxoedema’ refers to the accumulation of mucopolysaccharide in subcutaneous tissues. Milder symptoms are, however, more common. Special difficulties in diagnosis may arise:
CHILDREN WITH HYPOTHYROIDISM may not show classical features but often have a slow growth velocity, poor school performance and sometimes arrest of pubertal development.
YOUNG WOMEN WITH HYPOTHYROIDISM may not show obvious signs. Hypothyroidism should be excluded in all patients with oligomenorrhoea/ amenorrhoea, menorrhagia, infertility and hyperprolactinaemia.
AMONG THE ELDERLY, many of the clinical features are difficult to differentiate from normal ageing.



TSH is now the investigation of choice; a high TSH level confirms primary hypothyroidism. A low total or free T. level confirms the hypothyroid state and is especially important if there is any evidence of hypothalamic and pituitary disease, when TSH may be low or normal. Thyroid and other organ-specific antibodies may be
present. Other abnormalities include: ANAEMIA. This is usually normochromic and normocytic in type but it may be macrocytic (sometimes this is due to associated pernicious anaemia) or microcytic (in women, due to menorrhagia).



HYPONATRAEMIA due to an increase ill ADH and impaired free water clearance.

The signs of hypothyroidism. The bold type indicates signs of greater discriminant value.

The signs of hypothyroidism. The bold type
indicates signs of greater discriminant value.


Weight gain
Cold intolerance
Poor memory
Change in appearance
Poor libido
Puffy eyes
Dry, brittle, unmanageable hair
Dry, coarse skin
Menorrhagia or oligomenorrhoea in women
A history from a relative is often revealing
Symptoms of other autoimmune disease may be present


Replacement therapy with T. is given for life. The starting dose will depend upon the age and fitness of the patient, especially cardiac performance. In the young and fit, 100 ILgdaily is suitable, while 50 ILgdaily is more appropriate for the old or frail. T3 offers no significant advantage over T.

Patients with ischaemic heart disease require even lower initial doses, especially if the hypothyroidism is severe and long-standing. Most physicians would then begin with 25 ILgdaily and perform serial ECGs, increasing the dose at 2–{j week intervals if angina does not occur or worsen and the ECG does not deteriorate. Some, however, would use T3 beginning with 2.5 ILg8-hourly, doubling the dose every 48 hours up to 10 ILgthree times daily. If progress is satisfactory, T. (l00 ILgdaily) is then started and T3 is discontinued 5 days later. Adequacy of replacement should be assessed clinically and by thyroid function tests (TSH and possibly T.) after at least 6 weeks on a steady dose; the aim is to restore TSH to within the normal range. If serum TSH remains high, the dose of T. should be increased in 25-ILg increments and the tests repeated 6 weeks later. This stepwise progression should be continued until TSH becomes normal. The usual maintenance dose is 10G-200 ILggiven as a single daily dose; excessive replacement is probably dangerous.
Clinical improvement on T. may not begin for 2 weeks, though is quicker on T3′ and full resolution of symptoms may take 6 months. The importance of lifelong therapy must be emphasized and the possibility of other autoimmune endocrine disease developing, especially Addison’s disease, should be considered.

Borderline hypothyroidism or compensated euthyroidism

Patients are frequently seen with low normal serum T. levels and slightly raised TSH levels. Sometimes this follows surgery or radioiodine therapy when it can reasonably be seen as ‘compensatory’. Most physicians would now treat with T. where the TSH is above twice normal, or when possible symptoms are present, but would simply repeat the tests (and measure thyroid antibodies) 3–{j months later where TSH is only marginally raised.

Myxoedema coma

Though very rare, severe hypothyroidism, especially in the elderly, may present with confusion or even coma. Hypothermia is often present and the patient may have severe cardiac failure, hypoventilation, hypoglycaemia and hyponatraernia.
The mortality was previously at least 50% and patients require full intensive care. Optimal treatment is controversial and data lacking; most physicians would advise T3 orally or intravenously in doses of 2.5-5 ILgevery 8 hours, then increasing as above. Large intravenous doses should not be used.
Additional measures, though unproven, should include:
• Oxygen (by ventilation if necessary)
• Monitoring of cardiac output and pressures via Swan- Ganz catheter
• Gradual rewarming
• Hydrocortisone 100 mg i.v, 8-hourly
• Dextrose infusion to prevent hypoglycaemia

‘Myxoedema madness’

Depression is common but occasionally with severe hypothyroidism in the elderly the patient may become frankly demented or psychotic, sometimes with striking delusions. This may occur shortly after starting T. replacement.

Screening for hypothyroidism

The incidence of congenital hypothyroidism is approximately 1 : 3500 births. Untreated, severe hypothyroidism leads to permanent neurological and intellectual damage (‘cretinism’). Routine screening of the newborn using a blood-spot, as in the Guthrie test, to detect a high TSH level as an indicator of primary hypothyroidism is efficient; cretinism is prevented if T. is started within the first few months of life.
Screening of elderly patients is controversial but there is little doubt that the incidence of unsuspected thyroid disease in those over 65 years is 1-3%. With this and undiagnosed hyperthyroidism many physicians believe in screening of all elderly hospital attenders.

Posted by: brianna




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